This invention pertains generally to centerless grinding equipment and more paticularly to a method and apparatus for dressing regulating wheels for use in centerless grinding machines.
In centerless grinders the workpiece is carried on a support or blade between two rotating wheels, one of which is a grinding wheel rotating at a normal grinding speed. The other wheel is a regulating wheel which rotates in the same direction as the grinding wheel but at a much slower speed. The regulating wheel does not grind the workpiece but rotates it at a uniform speed against the grinding wheel, and the size of the finished workpiece is determined by the distance between the peripheral edges of the two wheels.
The axis of the regulating wheel is commonly inclined at a slight angle, known as the helix angle, with respect to the axis of the grinding wheel to cause the rotating workpieces to feed longitudinally past the face of the grinding wheel. The inclination is in a direction normal to the center line of the wheels, and the regulating wheel is formed with a longitudinally curved face to provide a desired relationship between the faces of the wheels. The curvature required is determined by the helix angle and the relationship desired, and it is difficult to define mathematically. For parallel faces and a helix angle on the order of 5.degree., for example, the face of the regulating wheel is slightly concave with a curvature which is generally parabolic toward the center and hyperbolic toward the ends. If the surface of the regulating wheel is to be inclined, e.g., for tapering workpieces fed a limited distance between the wheels or removing a predetermined amount of material from a workpiece fed through the wheels, the curvature must be adjusted accordingly.
Heretofore, regulating wheels have formed or dressed by a single point cutting tool, sometimes using a template of the desired curvature as a guide. This method is time consuming, and it generally requires a skilled technician both in the preparation of the template and in the actual dressing operation. Moreover, single point dressing tools are not suitable for use on some newer regulating wheels which are made of harder materials, e.g., diamonds, than wheels heretofore provided.